Spindle control for threading machines



Nov. 10, 1964 e. o. CONNER 3,156,122

SPINDLE CONTROL FOR THREADING MACHINES Original Filed March 12, 1951 3Sheets-Sheet 2 INVENTOR GUY 0. CON/V5? I I A TTUR/Vfy Nov. 10, 1964 G.o. CONNER SPINDLE CONTROL FOR THREADING MACHINES 3 Sheets-Sheet 3Original Filed March 12, 1951 INVENTOR GUY 0. GOIWVER United StatesPatent 3,156,122 SPINDLE CONTROL FOR THREADING MACHINES Guy 0. (Ionner,Cleveland, ()hio, assignor to Republic Steel (Iorporation, Cleveland,Ohio, a corporation of New Jersey Application Mar. 25, 1958, Ser. No.723,865, now Patent No. 3,036,319, dated May 29, 1962, which is adivision of application Ser. No. 215,131, Mar. 12, 1951, now Patent No.2,828,492, dated Apr. 1, 1958. Divided and this application .May 31,1961, Ser. No. 113,872

4 Claims. (Cl. 74-22) This invention pertains to machine tools forforming metal and more particularly to a machine adapted for high speedperformance of a variety of operations such as spinning, tapping,drilling, or the like. The invention has particular utility in thetapping or threading of nuts, and other operations similar to these.This application is a division of my application for United Statespatent, Serial No. 723,865, filed March 25, 1958, now United StatesPatent No. 3,036,319, for Tool Holder and Operating Means, which latterapplication was a division of my application for United States patent,Serial No. 215,131, filed March 12, 1951, for Nut Tapping Machine HavingReleasable Tap Holding Means to Discharge Tapped Nuts Therefrom, nowUnited States Patent No. 2,828,492.

This application concerns itself with the mechanism by which the toolspindles are controlled as they are driven through the workpieces. Inparticular, it is an object of this invention to provide a drum cam andfollower block arrangement which contributes greatly to "the performanceof the machine.

-A more complete understanding of the device of the invention, and theinvention itself, may be had by reference to the following descriptionand drawings which form a part of this specification.

In the drawings:

FIG. 1 is a longitudinal medial sectional view through the machine;

FIG. 2 is an enlarged sectional view of the spindle drive mechanism;

FIG. 3 is a partially exploded, end-elevational view of two of thefollower blocks and a portion of the drum cam showing the method ofremoval of the cam segments.

Briefly, my invention forms part of an automatic machine having one ormore horizontal spindles operated from a central shaft. The spindles, inaddition to being rotated about the central axis of the machine, revolveto drive a tool and are moved axially by a stationary drum cam. Thespindles are very accurately and firmly located to avoid misalignment orplay. The spindles are arranged around the central axis of the machinein two matched sets, each spindle having an axially aligned, matchingspindle facing it from the opposite set. Reference to my Patent2,828,492 will clarify any question concerning this arrangement. Toolholding heads are adapted to hold a tool very firmly yet are able torelease the tool to be picked up by the opposite head. Cam operated rodsextending through the spindles provide positively operated means forpassing the tool from one head to another. The tool is provided withshanks at both ends of the thread cutting part for the heads to grasp inorder for the tool to be passed in this manner. It is conceived,however, that for some operations, the tool will not be passed, but thatcomplementary tools may be held by opposing spindles thus performingdifferent types of operation.

The center of the machine between the two spindles is occupied by a workholding mechanism adapted to receive a workpiece for each pair ofspindles. The work holder securely clamps the workpiece in a fixedposition ice determined by a pilot part of the forming tool and is thusaccurately located relative to the spindles. The work holder carries theworkpiece along in fixed relation to the spindles to a discharge pointwhere it is discharged positively from the work holder.

My aforesaid Patent 2,828,492 contains a detailed disclosure of themachine in which the spindle control mechanism herein is employed.Therefore, the general characteristics of the machine will be heredescribed only to the extent necessary to an understanding of thespindle control mechanism.

The following more specific description will be made with reference tothe drawings and will pertain particularly to the machine as set up tothread nuts. It is not my purpose, however, so to limit my invention.

In FIG. 1 the character 10 designates the base on which the machine ismounted. A main drive motor (not shown) is mounted at one end of thebase and is connected to a drive shaft 12 by a suitable coupling. Thesupporting structure for the machine includes end standards 14 whichcomprise not only end supports for the machine but also housings for thegear drives and certain auxiliary equipment as will appear later.Auxiliary supports 16 for the center section are also mounted on thebase It). The supports 16 are merely legs carrying guide members 18.When the machine is in operation, suitable covers are employed toenclose the mechanism.

As is best shown in FIG. 1, the drive shaft 12 is journalled in ballbearings 29, in the left hand standard 1 A pinion 22 is mounted on theshaft 12 and is splined thereto such that it may be moved into or out ofengagement with a gear 24 by manipulating a fork shifting arrangementcomprising a shaft 26 to which is inred a shifting fork 28. This forkengages a groove 30 in a collar on the pinion 22 in a manner well knownin the art and thus is adapted to shift the pinion into and out ofdriving engagement with the gear 24.

The drive from the pinion is normally transmitted to the gear 24 andthence to a main drive shaft 32. The shaft 32 is journalled near its endin end bearings 34 in the outer walls of both standards 14 and also innear end bearings 36 in the inner walls. Still further support isprovided approximately midway between the center of the shaft and bothends by near center bearings 38 mounted in central stationary members40. These latter members are bolted or otherwise suitably mounted on theinner walls of the standards 14 at both ends. Thus the shaft issupported by six bearings. Firm support such as this is necessarybecause the shaft is the sole support of nearly all of the operatingmechanism of the machine. Furthermore, such support will help to preventwhipping of the long shaft. A thrust bearing 42 is provided at each endof the shaft. Adjustable cupped members 44 are fixed to the standards 14and on one end adjust the compressive force of a spring 46. A spacer 48is substituted for the spring 46 on the other end, but in other respectsthe devices on both ends are the same.

A pair of large bull or sun gears 50 are keyed to the shaft adjacent toand inboard of the near center bearings 38. These gears are the sungears for two symmetrical planetary gear system formed by planetarypinions 52 carried about the sun gears 50 by an irregular shaped drumsupported partly on the shaft by center bearings 54 and partly on thestationary members 40 by roller hearing 56. This drum is driven fromboth ends through internal ring gears 58, driven by pinions 60. Thepinions 60, in turn, are keyed to similar countershafts 62 journalled inbearing brackets 64 mounted on the inner wall of the standards 14. Thesecountershafts 62 are driven by the main shaft 32 through gears 66 keyedto the main shaft and meshing with gears 68 on the countershafts 62.

The main drum is substantially symmetrical end-for- C1 end, exceptdirectly at its center. The ring gears 58 are mounted on end plates 70which also support the roller bearings 56. These end plates 70 areconnected to the rest of the drum by cover members 72 which mayconveniently be bolted to the end plates 70 and to spindle supportingmembers 74. The spindle supporting members 74 are fastened to inner wallmembers 76 on both sides of the center section of the machine. Holes 78may be provided in the wall member 76 into which a bar may be insertedfor turning. the machine by hand if desired. The wall members 76 holdthe center bearings 54 and so help to support the drum. A center hub 80joins the wall members from both sides and completes the basic structureof the rotating drum. The hub 80 is the only part of the drum assemblywhich is not symmetrical, being formed with a shoulder 82 to which aface plate and clamping or work holding mechanism 84 is fastened. A

second spindle support member 86 (FIG. 2) may be bolted or otherwisefastened to the wall members 76 on each drum, and a cover plate 88 maybe used to cover the complete end of the assembly. The cover 88 andspindle support 86 slide freely relative to the guide member 18 and areparticularly useful to provide proper lubrication and flushing of chips.

A small oil pump 90 may be mounted in one of the end supports 14 toprovide lubrication for the gears and bearings in that support. The pumpis driven by a chain 92 engaged with a sprocket 94 on the main shaft anddriving a sprocket 96 on the pump shaft.

As noted above, the eight spindles on each side of the machine aredriven by the meshing engagement of the bull gears 50 with the pinions52 on the spindles (FIGS. 1 and 2). Each of the spindles is adapted forlongitudinal as well as rotary motion, thus being adapted to carrydriving heads which drive a tool in a rotary motion while feeding itthrough a nut blank, or other workpiece, and then following discharge ofthe finished nut, the heads carried by the spindles return the tool toits original position. It will be apparent that, while the shaft 32 isrotating in one direction, the spindle-carrying drum device will bedriven in the opposite direction because of the internal gear drive atthe ends of the drum. Thus, the pinions 52 are carried around the bullgears 50 in a planetary manner and consequently are driven at acomparatively high speed. The pinions 52 may be formed as a part of thespindle 98 itself or may be suitably fixed thereto. As best shown inFIG. 2, the spindle 98 extends through four of the individual members ofthe rotating drum. At its right hand end in that figure, the spindle isjournalled in a bronze bearing bushing 100 pressed into the supportmember 86. Suitable packing 102 is provided between the cover 88 and theflange of the bushing to keep dirt and chips isolated from the bearingswithin the drum member, and to keep cutting fluid and the like withinthe bushing as will appear hereinafter.

The spindle 98 next passes through the end wall member 76. At thispoint, a hardened steel bushing 104 is pressed into the member. Thesurface of the spindle adjacent this bushing is also hardened. A form ofball bearing which will journal the shaft both for rotational andlongitudinal motion is provided in the space between the bushing and thespindle. This bearing is formed by a sleeve 106 made of brass or similarmaterial and into which two or more circumferential rows of balls 108are staked in holes formed therein, This assembly of balls and retaineris placed blween the bushing 104 and the spindle shaft in that regionwhich then acts as races for the ball bearing. It is evident that, inaddition to the rotary motion of a regular ball bearing, the spindle canmove longitudinally, rolling the balls 108 on the bushing 104 andcausing the retainer and ball assembly to move longitudinally one-halfthe distance moved by the spindle. The bearing is formed so that theballs are pre oaded. That is, the diameters of the balls are slightlygreater than the space allowed for them between the bushing 104 and thespindle 98. This preload is preferably of the order of .0003 to .0005inch. A snap ring 110 may be provided for this hearing and may also beused for the others to hold standard oil seal rings in place, ifdesired.

The second and third spindle bearings are similarly formed andpreloaded. The second bearing 112 is located in an inwardly extending,wide flange 114 formed in the spindle support member 74. This bearingalso includes a hardened bushing 116 pressed into an opening in theflange 114 as a race for the hearing. The third bearing 118 includes abushing 120 pressed into the end plate 70 and on which the bearing mayroll. A cover plate 122 may be provided at this end to protect thebearings and retain grease.

At its end nearest the center of the machine, each spindle carries :1.tool holding head 124. The pinion 52 is located between the first andsecond bearings 106 and 112, and a follower block 126 which controls thelongitudinal movement of the spindle is located between the second andthird bearings. The spindles are journalled in the follower block by twocommercial angular contact ball bearings 128, one at each end of theblock. A fixed position of the spindle relative to the block ismaintained by engagement of one of the bearings with a shoulder 130 onthe spindle against which the bearing is held by the pressure of a nut132 against the other bearing. This nut is threaded on a threaded part134 of the spindle shaft and is retained by a jam nut 136. A flangedwasher 138 having portions bent over the flats of the nuts to preventrelative rotation therebetween is located between the nuts 132 and 136.The nut 132 may be partially bored out as shown (FIG. 2) to clear ashoulder 140 on the spindle.

As best shown in FIG. 3, the follower block 126 is an irregularly shapedblock having an outer surface of particylindrical form. A sheet 142 ofbrass or bronze or other bearing material covers this outer surface andis wrapped around the block having a tongue 146 extending between thetwo rollers 148 on each block. The rollers 148 may be standardanti-friction bearings mounted on headed pins threaded or otherwise heldin the block. They are spaced apart just far enough to straddle a camridge 150 formed on cam segment blocks 152 which are held in thestationary part 40 of the support for the machine. Thus, while therollers straddle the cam ridge 150, of this drum cam, they willtranslate any change in the location of that ridge into longitudinalmotion of the spindle. However, since the follower block is free torotate on the spindle, it is necessary to have some means of holding itin a fixed position with the rollers engaging the ridge. This isaccomplished by the engagement of the outer surface of the brass sheet142 with the inner surface of the cover member 72 which is finished as abearing surface for the follower blocks to slide on longitudinally.Because of their wide arcuate outer surface, the blocks are thenrestrained from turning about the spindles. Both the spindles 98 and thecover member 72 rotate about the center of the machine at the samespeed. Therefore, the only motion between the cover 72 and the followerblock is the longitudinal sliding induced by the cam.

In order to utilize the complete flexibility of the machine, it may benecessary at times to change the drum cam which controls the spindlemovement. Unless this can be done without removing the spindles, thewhole machine must be disassembled. Therefore, as shown in FIG. 3, thefollowers are designed to be moved to make possible the removal of thesegments 152. This is accomplished by otfsetting the rollers 148 fromthe spindles 98, so that the block 126 is eccentrically mounted and canrotate about the spindle when a cover 72 is removed to open a passagewaythrough which the cam segments may be removed. Each entire cam iscomposed of twelve segments so that the segments are not so large as tobe clumsy to manipulate, and the segmentization of the cam also permitsadjustment of certain of the segments to provide a chip-breaking action,described hereinbelow. This size cam also allows reasonably easy removalof the first segment between the spindles. Subsequent segments may bemore easily removed because they may slide around somewhat. The removalof each segment, however, is accomplished by loosening the holdingscrews and raising the segment somewhat and then tilting it as shown(FIG. 3) and bringing it out between the follower blocks. Installationof a new cam may be accomplished by reversing the operations. Thus, itis necessary only to remove the covers 72 preliminary to replacing adrum cam. This construction utilizes a close spacing of the spindles. Itwill be recognized that with a larger diameter machine or with fewerspindles, the spacing could be such as to allow removal of the segmentswithout a tilting follower. However, these possibilities increase thecost or reduce the production rate of the machine and therefore areundesirable.

Movement of the spindles 98 by the drum cam is effective to carry theheads 124 toward and away from each other and thereby to drive a tool154 through the blank and to pass it from one head to another. Thismovement may be modified to break chips formed by the tool in cuttingmaterial from the blank which may be desirable with certain classes ofmaterial, particularly when larger sizes of nuts are being threaded withthe production of chips of a length which may cause jamming of themechanism. This result is accomplished simply by offsetting certain ofthe cam segments 152 from the true line which the head would normallyfollow. This can be readily accomplished by grinding the cam to thedesired feed with the segment 150 in a given relative position and thenphysically moving some of the segments in a direction which would causea slight backing off of the tool cutting edge from the surface beingcut, the overall results being an oscillation of the tool as the threadsare cut. This motion is particularly desirable during the initial orroughing cuts, and the segments may be selectively offset to provide achip-breaking action primarily during that period of motion of the tool.The amount of the offset may be of the order of the depth of cut beingtaken by the tool or somewhat less. Thus, at the oifet segments, ifdesired, the cutting edge may be almost completely backed ofi, thusbreaking the chips. For most. operations, this offset of the segmentswill be only a few thousandths of an inch and will readily beaccommodated by the mounting of the segments. The reason such smalloffsets are efiective to produce the desired result is found in theroller type followers which fit snugly over the cam ridge 150 withsubstantially no clearance. This may be accomplished by preloading thefollowers. Therefore, any small variation in the cam is immediatelytransmitted from the follower through the spindle to the tool.

Precautions must be taken that the number of segments and the gear ratioof the spindle drive are not such that the tool is backed off eachrotation at the same rotative position of the tool. It will be apparent,if the tool is rotated an even fraction of a turn while the follower istraversing one segment, and with similarly offset segments, the cut willbe a wavy line. However, if the tool is rotated something other than aneven fraction, the initial cut will be wavy, but following cutting edgeswill smooth out the waves, because they will be retracted at otherpoints in the cut. Thus the final result is a uniformly smooth cut andis free from tearing because of jammed chips and also without wavesbecause of the proper proportions of the machine.

In some cases it might be desirable, however, to cut a wavy line such asin the case of a product whose finished threads are of a high finish,for example. In such cases it would be possible, with this type of camconstruction, to offset certain sized cam segments to produce an actionwhere the tool would cut first on one side of a thread and then theother to produce a wavy line. This wave could then be eliminated by asteady feeding final cut which would just shave off a very fine cut fromthe threads. This construction would require a longer tool with threadcutting edges ground for the particular cuts to be taken. The final cutbeing very thin could leave a fine finsh on the threads as desired.Variations of these arrangements will readily occur to those skilled inthe art.

In FIGS. 1 and 2 the tool-carrying head 124 is shown carried unsupportedat the end of the spindle. The specific construction and operation ofthe head is fully disclosed in my above-noted patent and application forpatent. It will, therefore, not be specifically described in thisapplication.

The tool is pushed out of the head by a rod 220 (FIG. 2) extendingthrough a central opening 222 in the spindle. The rod 220 is formed witha shoulder (not shown) adapted to engage the rear face of a toolretainer (not shown) in the head 124 to assure that it is moved to itsouter position in place to receive the tool when it is again picked upby the head.

Movement of the rod 229 is induced by a cam and follower arangement atthe oposite end of the spindle from the head (FIG. 2). At this end, acollar 230 is formed on the rod to engage a small ball thrust bearing232 held in a follower member 234. The follower member is freelyjournalled on the end of the spindle 98, so that it is carried by thespindle, but leaves the spindle free to rotate while the follower may besliding longitudinally of the spindle. A roller 236 journalled in themember 234 engages a cam track 238 which extends into a slotted openingin the member 234. A spring 240 engaging the member 234 and the cover122 urges the member 234 against the cam track 238, but in order toassure positive following by the follower, a radially extending roller242 may be used engaging the surface of a second cam track 244. Thetracks 238 and 24.4 may preferably be separate for ease of assembly.

In its operation, as explained heretofore, the machine in its preferredembodiment is driven with two motions. The shaft 32 carrying the bullgears 50' rotates in a direction such that the top of the gears areapproaching the observer in all figures. The drum carrying the spindlesand work holding device rotates in the opposite direction.

From the foregoing description, it can be seen that the spindle cam andthe push rod cam 238 could be substantially parallel for all except avery small part of the travel of the spindles. Since this is true, it isobvious that the push rod 220 could be carried with spindles throughoutmost of their travel, and only short wedge-shaped cams used wherenecessary, to push the tool out of the respective heads. If such camswere to be used, the follower could be merely the end of the push rodwhich could slide on the cam for a short distance, or the follower couldbe formed by a. ball retained on the end of the rod.

During the movement of the spindles longitudinally, they are alsorotated because of the meshing of the pinions 52 with the gear 50. Sincethe spindles on one side are driven in unison with those on the oppositeside, they are always in position to pass and receive the tool, and bothare effective to drive the tool during the threading operation. Thepreloaded bearings 106, 112 and 118 are capable of both rotary andlongitudinal motion, thus insuring a complete lack of play or whip inthe spindles. Thus, the spindles are always true, and since the nutblanks are true, and both tool and blank are securely held, the threadswill be cut to much closer tolerances than with prior machines using theconventional type hook tap.

It will be recognized that the number of spindles in a machine builtaccording to my invention is not fixed, but

that more or fewer could be used. If more spindles were used and themachine driven at the same rotational speed, the output would beproportionately faster. Thus it is possible with a multi-spindle machineto produce as many as 2500 nuts per minute as compared with present dayproduction with conventional machines of from 50 100 nuts per minute.Moreover, the tool is no more expensive and perhaps less expensive thanpresent day hook taps and, if made of suitable material, will lastseveral times as long measured by the number of nuts produced per tap.This is true because of the complete lack of undesired relative motionbetween the tap and the nut blank, and because the use of fine fastcutting materials is feasible only with such a small tool. Thus myinvention makes possible not only a greater production, but the upkeepcost, so far as tools go, is considerably less.

While the novel features of the invention have been illustrated anddescribed in connection with specific embodiments of the invention, itis believed that these embodiments will enable others skilled in the artto apply the principles of the convention in forms departing from theexemplary embodiments herein, and such departures are contemplated bythe claims.

What is claimed is:

1. Mechanism for controlling the longitudinal position of a rotatableand longitudinally movable tool driving spindle in a metal workingmachine comprising: a drum cam mounted in said machine having a camridge thereon, a tiltable block rotatably journalled but longitudinallyfixed on said spindle, said spindle extending through said blockeccentrically thereof, rollers mounted on said block on axesperpendicular to and displaced from the axis of said spindle, saidrollers being positioned to fit snugly, one on each side of said ridgesaid block being formed \vith an arcuate surface opposite said rollers,and a. removable annular surface in said machine adapted for slidingengagement by the arcuate surface of said block to prevent rotation ofsaid block with said spindle and to permit said block to rotate awayfrom said cam ridge when said annular surface is removed.

2. Mechanism for controlling the longitudinal position they are beingformed, follower means for said cam comprising a block rotatablyjournalled but longitudinally fixed on said spindle, means extendingfrom said block adapted to contact both sides of said ridge whereby thelongitudinal movement of said block and said spindle is controlled, anannular bearing surface in said machine,

and a face on said block in sliding contact with said annular bearingsurface whereby said block is held against rotation with said spindle.

3. Mechanism for controlling the longitudinal position of a rotatableand longitudinally movable tool driving spindle in a metal workingmachine comprising: a cam drum, a cam comprising a plurality of segmcntsmounted on said drum, each said segment being formed with a ridgethereon, said cam ridge being formed along a line adapted to advancesaid spindle toward a workpiece at a fixed predetermined rate and someof said segments being offset in a direction axial of said drum to causewithdrawal of said spindle a distance substantially equal to thethickness of a out being taken on such workpiece effective toperiodically break chips as they are being formed, follower means forsaid cam comprising a block rotatably journalled but longitudinallyfixed on said spindle, means extending from said block adapted tocontact both sides of said ridge whereby the longitudinal movement ofsaid block and said spindle is controlled, an annular bearing surface insaid machine, and a face on said lock in sliding contact with saidannular bearing surface whereby said block is held against rotation withsaid spindle.

4. Mechansrn for controlling the longitudinal position of a rotatableand longitudinally movable tool driving spindle in a metal workingmachine comprising: a drum cam composed of a plurality of removablesegments mounted in said machine, a block rotatably journalled butlongitudinally fixed on said spindle, said spindle extending throughsaid block eccentrically thereof, cam following rollers mounted on saidblock on axes perpendicular to and displaced from the axis of saidspindle, said rollers being pcsitioned to fit snugly, one on each sideof said ridge, said block being formed with a bearing Surface oppositesaid roller, and fixed annular bearing surface in said machine adaptedfor sliding engagement by said bearing surface of said block to preventrotation of said block with said spindle, said fixed bearing surfacebeing removably mounted in said machine such that said block is tiltableon said spindle for the removal of cam segments when said fixed bearingsurface is removed.

References Cited in the file of this patent UNITED STATES PATENTS953,651 West Mar. 29, 1910 977,488 Traub Dec. 6, 1910 1,034,436Fishburne Aug. 6, 1912 1,808,083 Tibbelts June 2, 1931 1,928,529 GarrardSept. 26, 1933 1,934,044 De Leeuw Nov. 7, 1933 1,990,188 Kabbel Feb. 5,1935 2,322,340 Bechler June 22, 1943 2,828,492 Conner Apr. 1, 1958

1. MECHANISM FOR CONTROLLING THE LONGITUDINAL POSITION OF A ROTATABLEAND LONGITUDINALLY MOVABLE TOOL DRIVING SPINDLE IN A METAL WORKINGMACHINE COMPRISING: A DRUM CAM MOUNTED IN SAID MACHINE HAVING A CAMRIDGE THEREON, A TILTABLE BLOCK ROTATABLY JOURNALLED BUT LONGITUDINALLYFIXED ON SAID SPINDLE, SAID SPINDLE EXTENDING THROUGH SAID BLOCKECCENTRICALLY THEREOF, ROLLERS MOUNTED ON SAID BLOCK ON AXESPERPENDICULAR TO AND DISPLACED FROM THE AXIS OF SAID SPINDLE, SAIDROLLERS BEING POSITIONED TO FIT SNUGLY, ONE ON EACH SIDE OF SAID RIDGESAID BLOCK BEING FORMED WITH AN ARCUATE SURFACE OPPOSITE SAID ROLLERS,AND A REMOVABLE ANNULAR SURFACE IN SAID MACHINE ADAPTED FOR SLIDINGENGAGEMENT BY THE ARCUATE SURFACE OF SAID BLOCK TO PREVENT ROTATION OFSAID BLOCK WITH SAID SPINDLE AND TO PERMIT SAID BLOCK TO ROTATE AWAYFROM SAID CAM RIDGE WHEN SAID ANNULAR SURFACE IS REMOVED.